21517149 has 4 divisors (see below), whose sum is σ = 28689536. Its totient is φ = 14344764.

The previous prime is 21517127. The next prime is 21517163. The reversal of 21517149 is 94171512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21517149 - 2⁷ = 21517021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21517109) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3586189 + ... + 3586194.

It is an arithmetic number, because the mean of its divisors is an integer number (7172384).

Almost surely, 2^21517149 is an apocalyptic number.

It is an amenable number.

21517149 is a deficient number, since it is larger than the sum of its proper divisors (7172387).

21517149 is an equidigital number, since it uses as much as digits as its factorization.

21517149 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7172386.

The product of its digits is 2520, while the sum is 30.

The square root of 21517149 is about 4638.6581033743. The cubic root of 21517149 is about 278.1387994500.

It can be divided in two parts, 2 and 1517149, that added together give a palindrome (1517151).

The spelling of 21517149 in words is "twenty-one million, five hundred seventeen thousand, one hundred forty-nine".